# GNU Guix --- Functional package management for GNU
# Copyright © 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
# Copyright © 2021 Tobias Geerinck-Rice <me@tobias.gr>
#
# This file is part of GNU Guix.
#
# GNU Guix is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or (at
# your option) any later version.
#
# GNU Guix is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

# Bash completion for Guix commands.

declare _guix_available_packages
declare _guix_commands

_guix_complete_command ()
{
    local word_at_point="${COMP_WORDS[$COMP_CWORD]}"
    if [ -z "$_guix_commands" ]
    then
	# Cache the list of commands to speed things up.
	_guix_commands="$(guix --help 2> /dev/null  \
                                     | grep '^    ' \
				     | sed '-es/^ *\([a-z-]\+\).*$/\1/g')"
    fi
    COMPREPLY=($(compgen -W "$_guix_commands" -- "$word_at_point"))
}

_guix_complete_subcommand ()
{
    local command="${COMP_WORDS[1]}"
    local subcommands="$(${COMP_WORDS[0]} $command --help 2> /dev/null \
                         | grep '^   [a-z]' \
                         | sed -e's/^ \+\([a-z-]\+\).*$/\1/g')"
    COMPREPLY=($(compgen -W "$subcommands" -- "${COMP_WORDS[$COMP_CWORD]}"))
}

_guix_complete_available_package ()
{
    local prefix="$1"
    if [ -z "$_guix_available_packages" ]
    then
	# Cache the complete list because it rarely changes and makes
	# completion much faster.
	_guix_available_packages="$(${COMP_WORDS[0]} package -A 2> /dev/null \
                                    | cut -f1)"
    fi
    COMPREPLY=($(compgen -W "$_guix_available_packages" -- "$prefix"))
}

_guix_complete_installed_package ()
{
    # Here we do not cache the list of installed packages because that
    # may change over time and the list is relatively small anyway.
    local prefix="$1"
    local packages="$(${COMP_WORDS[0]} package -I "^$prefix" 2> /dev/null \
                      | cut -f1)"
    COMPREPLY=($(compgen -W "$packages" -- "$prefix"))
}

_guix_complete_option ()
{
    local command="${COMP_WORDS[$1]}"
    local subcommand="${COMP_WORDS[$(($1 + 1))]}"
    if _guix_is_option "$subcommand"
    then
	subcommand=""
    fi
    local options="$(${COMP_WORDS[0]} $command $subcommand --help 2> /dev/null \
                            | grep '^  \+-' \
                            | sed -e's/^.*--\([a-zA-Z0-9_-]\+\)\(=\?\).*/--\1\2/g')"
    compopt -o nospace
    COMPREPLY=($(compgen -W "$options" -- "$2"))
}

_guix_is_option ()
{
    case "$1" in
	-*)
	    true
	    ;;
	*)
	    false
	    ;;
    esac
}

_guix_is_removing ()
{
    local word
    local result="false"
    for word in ${COMP_WORDS[*]}
    do
	case "$word" in
	    --remove|--remove=*|-r)
		result=true
		break
		;;
	esac
    done
    $result
}

_guix_is_dash_f ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-f" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --file=*|--install-from-file=*) true;;
		 *)                              false;;
	     esac }
}

_guix_is_dash_l ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-l" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --load=*) true;;
		 *)        false;;
	     esac }
}

_guix_is_dash_L ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-L" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --load-path=*) true;;
		 *)             false;;
	     esac }
}

_guix_is_dash_m ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-m" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --manifest=*) true;;
		 *)            false;;
	     esac }
}

_guix_is_dash_C ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-C" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --channels=*)  true;;
		 *)             false;;
	     esac }
}

_guix_is_dash_p ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-p" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --profile=*)   true;;
		 *)             false;;
	     esac }
}

_guix_complete_file ()
{
    # Let Readline complete file names.
    compopt -o default
    COMPREPLY=()
}

_guix_complete_pid ()
{
    local pids="$(cd /proc; echo [0-9]*)"
    COMPREPLY=($(compgen -W "$pids" -- "$1"))
}

_guix_complete ()
{
    local word_count=${#COMP_WORDS[*]}
    local word_at_point="${COMP_WORDS[$COMP_CWORD]}"

    # Find the innermost command at point, e.g. "build" in the case of
    # "guix time-machine OPTIONS -- build<Tab>" -- but "time-machine" if
    # point is moved before "build".
    local command_index=0
    local command
    local word_index=0
    local word
    local expect_command="true"
    while [[ $((++word_index)) -le COMP_CWORD ]]
    do
	word="${COMP_WORDS[$word_index]}"
	if $expect_command
	then
	    command_index=$word_index
	    command="$word"
	    expect_command="false"
	    continue
	fi
	if [[ "$word" = "--" ]]
	then
	    case "$command" in
		environment)
		    break
		    ;;
		time-machine)
		    expect_command="true"
		    ;;
	    esac
	fi
    done

    case $COMP_CWORD in
	$command_index)
	    _guix_complete_command
	    ;;
	*)
	    if [[ "$command" = "package" ]]
	    then
		if _guix_is_dash_L || _guix_is_dash_m || _guix_is_dash_p || _guix_is_dash_f
		then
		    _guix_complete_file
		elif _guix_is_removing
		then
		    _guix_complete_installed_package "$word_at_point"
		else
		    _guix_complete_available_package "$word_at_point"
		fi
	    elif [[ "$command" = "install" ]]
	    then
                if _guix_is_dash_L || _guix_is_dash_m || _guix_is_dash_p
                then
                    _guix_complete_file
		else
		    _guix_complete_available_package "$word_at_point"
		fi
	    elif [[ "$command" = "remove" ]]
	    then
                if _guix_is_dash_L || _guix_is_dash_m || _guix_is_dash_p
                then
                    _guix_complete_file
		else
		    _guix_complete_installed_package "$word_at_point"
		fi
	    elif [[ "$command" = "upgrade" ]]
	    then
                if _guix_is_dash_L || _guix_is_dash_m || _guix_is_dash_p
                then
                    _guix_complete_file
		else
		    _guix_complete_installed_package "$word_at_point"
		fi
            elif [[ "$command" = "build" ]]
            then
                if _guix_is_dash_L || _guix_is_dash_m || _guix_is_dash_f
                then
                    _guix_complete_file
		else
		    _guix_complete_available_package "$word_at_point"
                fi
	    elif [[ "$command" = "environment" ]]
	    then
                if _guix_is_dash_L || _guix_is_dash_m || _guix_is_dash_p || _guix_is_dash_l
                then
                    _guix_complete_file
		elif _guix_is_option "$word_at_point"
		then
		    _guix_complete_option "$command_index" "$word_at_point"
		else
		    _guix_complete_available_package "$word_at_point"
		fi
	    elif [[ "$command" = "download" ]]
	    then
		 _guix_complete_file
	    elif [[ "$command" = "system" ]]
	    then
		case $COMP_CWORD in
		    2) _guix_complete_subcommand;;
		    *) _guix_complete_file;; # TODO: restrict to *.scm
		esac
            elif [[ "$command" = "pull" ]]
            then
                if _guix_is_dash_C || _guix_is_dash_p
                then
                    _guix_complete_file
                fi
            elif [[ "$command" = "time-machine" ]]
            then
                if _guix_is_dash_C
                then
                    _guix_complete_file
		else
		    _guix_complete_option "$command_index" "$word_at_point"
                fi
	    elif [[ "$command" = "container" ]]
	    then
		case $COMP_CWORD in
		    2) _guix_complete_subcommand;;
		    3) _guix_complete_pid "$word_at_point";;
		    *) _guix_complete_file;;
		esac
	    elif [[ "$command" = "import" ]]
	    then
		_guix_complete_subcommand
	    elif [[ "$command" = "hash" || "$command" = "gc" ]]
	    then
		_guix_complete_file
            elif [[ "$command" = "weather" ]]
            then
                if _guix_is_dash_m
                then
                    _guix_complete_file
                fi
	    else
		_guix_complete_available_package "$word_at_point"
	    fi
	    ;;
    esac

    if [[ -z "$COMPREPLY" && COMP_CWORD -gt command_index ]] &&
        _guix_is_option "$word_at_point"
    then
	_guix_complete_option "$command_index" "$word_at_point"
    fi
}

complete -F _guix_complete guix
